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From: Andres Freund <andres@2ndquadrant.com>
To: Josh Berkus <josh@agliodbs.com>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
Cc: Graeme B. Bell <grb@skogoglandskap.no>
Subject: Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
Date: Fri, 22 Aug 2014 16:02:23 +0200
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On 2014-08-21 14:02:26 -0700, Josh Berkus wrote:
> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
> > Not sure how you can make such a blanket statement when so many people
> > have tested and shown the benefits of hyper-threading.  
> 
> Actually, I don't know that anyone has posted the benefits of HT.
> Link?

There's definitely cases where it can help. But it's highly workload
*and* hardware dependent.

> OS is RHEL with 2.6.32-431.3.1.el6.x86_64.
> 
> I've emailed a kernel hacker who works at Intel for comment; for one
> thing, I'm wondering if the older kernel version is a problem for a
> system like this.

I'm not sure if it has been backported by redhat, but there
definitely have been significant improvement in SMT aware scheduling
after vanilla 2.6.32.

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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  Subject: Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
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